A refrigerated transport is a means of carrying perishable products such fruits, meats, vegetables, dairy products, pharmaceuticals, chemicals and other things that need to be kept in controlled conditions. In a refrigerated transport, products will be contained in a cargo box and the temperature within the cargo box will be kept within a predetermined temperature range to keep the products in a good-quality condition, dependent upon whether the products require a cool or frozen environment. Particularly, in the food industry, the refrigerated transport is an essential link in a food supply chain.
Usually, in refrigerated transport, energy consumption, such as power consumption, is relatively high due to varying ambiences, application types and operating cycles. Thus, energy saving becomes an important problem in many of refrigerated transport applications. Another concern is to maintain temperature integrity for the products, since violations of temperature requirements could cause an undesirable quality loss of products. In refrigerated transport applications, a traditional solution of controlling temperature is a feedback based automation system, in which the air temperature representing a cargo box temperature is measured in real time and fed back to a controller to determine operations of a refrigeration unit, for example switching the refrigeration unit on or off, or adjusting variable frequencies of the refrigeration unit. During a door opening event for product loading or uploading, the traditional feedback based automation system is closed and at that time one or more curtains are usually used, for example, at rear and/or side doors to prevent a sharp increase of temperature during the door opening event. Although this is an easily implemented way for temperature maintenance and can prevent a sharp increase of temperature to a certain degree, it is hard to maintain the temperature integrity for the products since the temperature is still increased unavoidably due to the door opening event.